class_docstr: A component to parse the output of a Generator to `Answer` objects using regular expressions.
code: def _extract_reference_idxs(
      reply: str, reference_pattern: str
  ) -> List[int]:
      document_idxs = re.findall(reference_pattern, reply)
      return [int(idx) - 1 for idx in document_idxs]
  
file_path: haystack/haystack/components/builders/answer_builder.py
imports: import logging
  import re
  from typing import List, Dict, Any, Optional
  from haystack import component, GeneratedAnswer, Document
label_desc: Use image node_id 4 for calling the AnswerBuilder obj's underlying member method code with example usage: obj._extract_reference_idxs(reply, reference_pattern) and returns: unknown